Apple's iOS platform is believed to take in about 90 percent of all dollars spent on mobile devices, highlighting the revenue advantage for iPhone and iPad developers when compared to Google's Android.

Analyst Gene Munster with Piper Jaffray said on Monday that he believes Google's Android Market has generated about 7 percent of the gross revenue that Apple's App Store has raked in since its inception.

"In other words, it appears that Apple has roughly 85-90% market share in dollars spent on mobile applications," he wrote in a note to investors. "While Google has closed the gap in terms of app dollars spent over the last year and we continue to believe Android will grow smartphone share faster than Apple, we believe Apple is likely to maintain 70%+ share of mobile app dollars spent over the next 3-4 years."

The estimates reached by Piper Jaffray come from numbers publicly revealed by Apple, as well as data from Androlib, an Android application discovery tool. Munster said that he believes about $330 million has been generated on the Android Market to date, while only 1.3 percent of the applications on the Android Market are paid.

"Thus, with 6.75 billion total app downloads to date, we believe roughly 90 million of those were paid apps," he said of Android. "As a comparison, we estimate that Apple has generated $4.9 billion in gross sales since inception through the September quarter and that 14% of total app downloads on the App Store have been paid apps."

In terms of average selling prices, Munster's numbers suggest that Android users pay more for a single application, but download fewer paid applications overall. The top 50 paid Android applications have an average selling price of $3.79, compared to an average selling price of $2.01 on Apple's App Store.

Based on the fact that Google has activated 200 million total Android devices, Munster has estimated that there are an average of 34 applications on each Android device. That compares to about 71 applications on each iOS device.

In June, Munster polled developers at Apple's annual Worldwide Developers Conference, and found that 47 percent of respondents develop applications for Google Android as well as Apple's iOS. But all 45 developers he spoke with said that iOS is the easiest platform for development and the best to monetize an application.

Highlighting the importance of mobile application stores in the future, one estimate has called for platforms like iOS and Android to generate $14 billion in direct revenue in 2012. While the volume of applications downloaded on Android is expected to surpass the iOS App Store, Apple's iPhone, iPad and iPod touch platform is expected to generate $2.86 billion in application revenue by 2016, compared to just $1.5 billion on Android.